My chickens won't touch popcorn, either. They also don't like brown bread, but white is okay. I tried green beans - talk about stink-eye! They will eat pumpkin when there's nothing else around. They absolutely love watermelon. Tomatoes were a no go. My one RIR stole a feeder fish from the ducks the other day. I'm going to go into town to get some cabbage since I read the threads on that.
Haven't made them their own dust bath yet - between them and the dog, they have turned the whole back yard into one!